The present invention generally relates to a control device in use with an image recording apparatus, and more particularly, to a control device in use with an image recording apparatus for causing the image recording apparatus to output graphic data as generated by a computer, e.g., a host computer.
The image recording apparatus, which visually outputs an image of the graphic data (vector data) as is generated by a computer generating and supplying graphic data, e.g., a host computer, comes in two varieties, an electrostatic plotter and a called Xerography plotter.
The electrostatic plotter directly forms an electrostatic latent image on an electrostatic recording paper by a recording head of the multi-needle electrode type, and applies a subsequent developing process to the latent image, and finally produces an image in a visual manner. The Xerography plotter (referred to as an XP plotter) forms an electrostatic latent image on a photosensitive drum, and transforms the latent image into a visible image, and finally transfers it on normal paper.
Some types of the image recording apparatuses use recording papers of some different sizes in accordance with the sizes of the set-of-drawings, which is output for the input image data (an XP plotter of this type is provided with a plurality of trays containing papers of different sizes, and for outputting a drawing of the image data, a tray corresponding to the size of the set-of-drawings is selected and the image data is output onto the paper in the selected tray).
In a conventional control device in use with the above image recording apparatus, the graphic data (vector data) as is generated by and transferred from a host computer is converted into raster image data. When the image recording apparatus is ready for the outputting of the image data, the converted image data is transferred to the image recording apparatus, and the image (visible output) is output from the image recording apparatus. When the image recording apparatus is not in a ready-for-drawings-output state, viz., when the paper of a size amounting to an image size of the image data of a set of drawings (referred to as set-of-drawings size paper), is absent, the transfer of the image data is ceased till the image recording apparatus is in a ready-for-drawings-output state (viz., the supply of the set-of-drawings size paper is completed). When the image recording apparatus is in a ready-for-drawings-output state, the image data is transferred to the image recording apparatus, the image (visible output) is output from the image recording apparatus.
In transferring the image data of the set of drawings to the image recording apparatus, when the set-of-drawings size paper is absent, the conventional control device decides that the image recording apparatus cannot output a drawing, and ceases the transfer of the image data. At this time, it is assumed that the host computer generates the image data of another set of drawings and when the paper of a size amounting to the generated image data is present in the image recording apparatus. In this case, the paper of the output size corresponding to the additional image data should be present in the image recording apparatus. Therefore, although the image recording apparatus can output the drawing of the image data corresponding to the additional image data, it does not execute the output processing of the next generated image data until the output processing of the previously transferred image data is completed, viz., the supply of the paper whose size amounts to the previously generated image data is completed, and the output processing of the previously transferred image data is completed. Therefore, much time is taken for the image outputting operation.
Additionally, the host computer must retain the next generated image data of the set of drawings till the outputting of the previously generated and transferred image data of the set of drawings is completed. During this time period, the host computer is inhibited from engaging in other jobs, resulting in poor rate of operation of the host computer.